Nightfall

Sun goes down, and night goes on.
So far, it has been repeated on several occasions.

Rainy season

梅雨(Tsuyu, Baiu) is rainy period that comes along every year from May to July in Japan.
Hydrangea(紫陽花, Ajisai) is represent of the rainy season flower.

Rays of the sun

Covered with clouds, and reflected lines.
If there wasn't such situation, I couldn't see.